For Paris Saint-Germain, this Champions League second leg against Real Madrid is not just about qualification and the club's entire season, but also about their team's entire identity.

It's also not just about the negative identity developed from yet again going out to one of the traditional powers they so want to usurp, and how a comeback of this size would erode so much of the fatalist stigma from last season's shambolic defeat.

It's largely about what happened after that - and now the absence of Neymar.

The Brazilian's world-record signing was rightfully seen as moving the club onto a new level in terms of the market, and that has happened, but it hasn't quite had the same effect on their status, on their perception.

Some of the leaked stories around Neymar, and even all the uncertainty surrounding his operation and manager Unai Emery initially insisting he wouldn't need one, have painted a less serious picture than had maybe been anticipated.

Whether right or wrong, the image has grown of a side where the superstar has been indulged - both in terms of his role and even as regards the ease of domestic wins - rather than one that is putting in place a proper collective with a deeper philosophy.

Now, without the playmaker that has been so central to everything they do, PSG must overturn a 3-1 deficit against the club that has won the last two Champions Leagues and 12 overall. That is ominous.

It's at points like this when the Ewing Theory is brought up and where that issue of identity comes in. Whatever about what defeat without Neymar would mean, what would qualification without him mean? What a moment of maturation for Emery's side that would be.

Stronger

"Our team, even without Neymar, is able to beat the best Real Madrid team," said Emery.

"With Neymar, PSG is stronger, but we are still strong without him," full back Dani Alves said. "There are two options: either we sit and cry, or we stand on our feet and fight."

It is possible that the absence of Neymar will allow Emery more space to put in place a specific game-plan; that it will rally other players; that it will allow Kylian Mbappe the stage to properly thrive himself and bring out the best in what remains a stellar squad.

It could also shift emphasis, alter the dynamic of the game.

One of the members of that squad that was previously the prince is Marco Verratti, and he could be central to this in so many ways.

For a start, there is probably a pressure on him to step up and take command in such a game.

Secondly, his exact type of game should be what imposes a tactical philosophy on PSG, in the same way that Luka Modric and Toni Kroos do for Real. And this is where it might get very interesting.

There is still the possibility that those two midfielders could miss out through injury. That would create a tactical issue for Zinedine Zidane, and essentially cede control of the game to PSG. Real will have to adapt - and it could be a nervy night.

It should be noted that former Real star Angel Di Maria has been in rampaging form when used, and the way he can just slot into this side emphasises how good this PSG team is; how much quality there is in it.

They are just missing a win like this, a unifying event which is what Alves demanded when he called on his team to "send out a message to Europe".

"It's a challenge for us, an opportunity to change the course of our history and eliminate the holders of the title," added the 34-year-old. "We could have had a better result in the first leg. We were superior in the game and had the better chances. It made us think we can knock them out.

"There is no greater motivation. We are going to try to knock out a strong opponent and send a message to Europe. We have to start the match with this mentality. We have to believe and we have to do it."

As well as an iconic moment, they are also missing the identity and deeper assurance that Real possess in spades. One little story from the start of the Champions League perfectly indicates this.

Sergio Ramos was due to give a short interview ahead of a Uefa presentation, one of those that tends to be neutral enough. Just before they went on stage, though, the defender insisted that the interviewer ask him about winning three in a row.

There was no reticence about it, no bland chat about taking each game as it comes, and seeing what happens.

He wanted everyone to see that Real now feel the Champions League trophy is their own; that it's going to be a proper fight to prise it away from them.

This is what PSG are up against. It's going to require an effort that goes right to the core of the side.